Re: 40 Hz RIP (DeLiang Wang )

Subject: Re: 40 Hz RIP
From:    DeLiang Wang  <dwang(at)CIS.OHIO-STATE.EDU>
Date:    Wed, 28 May 1997 09:51:30 -0400

Neil,

> > The vision community is a better place to voice your complaints,
>
> Now hang on just a minute DeLiang. You have made some grand
> claims concerning the application of the "oscillatory
> framework" to both visual and auditory processing. Also, as you
> will admit, apart from the references I have given above, the
> experimental literature you have been using to support your
> auditory models is *visual*. It is therefore perfectly
> legitimate for us to question the nature of that visual
> evidence. We have some very good vision people here in
> Manchester with whom I am in regular contact.

The reason I said that your doubts on experimental findings in the visual
system should be expressed to the vision community is quite obvious: We,
on the auditory list, are not experts (forgive me if some of you are) on
visual experiments and thus can't judge the value of your doubts. Further,
if your doubts have any value, you could make a contribution by raising them
to those experimentists who work on these topics, such as Wolf Singer.

As most of you would agree, those people who report coherent oscillations in
the visual system are well-respected experimentalists and the vision community
is full of smart critics. Relating to your specific doubts that visual
experimentalists forget eye movements, here is a quote from a recent paper
by A. Kreiter and W. Singer (1996) who report coherent oscillations in
awake monkeys: "Similarly, the failure to find sharp stimulus-induced peaks
... excludes the possibility that eye movements may have caused the
correlations" (J. Neurosci., vol. 16, p. 2391). Let me repeat, we am not in
a good position to judge doubts on experiments.

Those of you who have read our papers will notice that we quoted more than
the list provided by Neil on auditory experiments (e.g. several papers from
R. Llinas' group in NYU). Plus, the literature is evolving.

> > The above idea was used in an early paper on oscillatory
> > associative memory
> > (Wang, Buhmann, and von der Malsburg, 1990, refs. below) to handle the
> > overlap problem, essentially the same as the above problem.
> > But the oscillator
> > model used there proves to be too clumpsy. A recent model by
> > Brown and Wang
> > (1996) explicitly addressed the problem of "duplex
> > perception" in audition
> > using the same idea. But the Brown/Wang model is based on
> > relaxation
> > oscillator networks, which have an elegant theory and
> > computational properties
> > behind (see below).
>
> It is clear that the in the first scheme you envisaged the
> frequency of the oscillators had only an arbitrary relationship
> to the objects or features they were binding, i.e. there is
> nothing double about the relationship between TABLE and BALL.

In Fig. 3 of our paper (I forgot to give ref. last time, it is in Neural
Computation, vol. 2, pp. 94-106), the overlapping parts between different
patterns oscillate with either double frequency of bursts or triple frequency.
One can easily link that simulation with 3 patterns to the current example of
RED, BLUE, TABLE (I wish that we could foresee the current debate and thus
label those patterns accordingly :-) ).

> i.e. it is itself a signal. Any further oscillatory computation
> is entirely redundent.

I are not aware of any advocate of the oscillatory framework who says that
you need oscillations for EVERYTHING. Auditory modeling existed long before
the notion of temporal correlation was introduced. As I emphasized repeatedly
in my first message of May 20, oscillatory correlation is a representation, and
computation is a different dimension. Even as a representation, it is one
alternative. Those of us who work on oscillatory correlation see computational
advantages, but no surprise that other studies don't use this
representation. And in this case, of course, it is redundant, just like
the representation you use is redundent from our perspective.

I am sure that most have had enough with this debate, and I hope that I have
made my understanding of oscillatory correlation clear. If any of you in
the auditory list still have questions, you are more than welcome to
communicate with me privately as some did already.

Cheers,
DeLiang